All hail the automatic heater

[soup dragon]

Excellent thread,i now know what that buzzer looking thing on the dash is as well as the odd looking contraption behind the ashtray

[trader220]

Well my cars warm and dry away from the snow right now so no pics. The Dial has 3 numbers that how in a little window as you turn it. It feels like they do nothing at all. The heat cranks as you pull up each red lever.

[ausdilecce]

trader220,
Ahhh, ok

I *am* guessing but I would think that is NOT autoheat. If you have 3 numbers, that might be for kickpanel fan speed only and you manually control heat output with the red levers..

Real autoheat has 0 - 9 and a defrost symbol on the dial and NO levers.. There are thermostats right after the control boxes (after the heat exchangers ) as well as a cabin temp sensor that all feed into the control box ( under the dial ) to regulate heat on settings 0-9. Defrost is : all fans on high speed and NO heat regulation

tonythetarga,
If you only have one speed ( others are not working ) then there is probably something wrong with your 'footwell series resistor' ( look for it in imcarthur's post ) .. That thing is responsible for fan speed.


cactusdtd, love the idea of having blue for AC, white for fresh air and red for heat..
Good luck

[emcon5]

Originally posted by ausdilecce
Real autoheat has 0 - 9 and a defrost symbol on the dial and NO levers..

Mine has a single lever, which moves up and down via the servo in the auto-heat controller. As I understand it, they did away with the lever on later models.

Tom

[imcarthur]

Revised including AC. I called it cool rather than cold. We all know . . .

Comments/Corrections?

Note: This is a 1987 Autoheat Only diagram.

Edited: See next Post

[imcarthur]

Pic deleted - see below

[cactusdtd]

Ian

Awesome dude.......I knew you couldn't resist!!!!!

Now for my update. After reading the last post I went to the garage (in SC my '87 doesn't sleep for the winter ) and tested all the controls and outlets. I then confirmed it with my buddy's '88. Here goes:

1. The defroster vents on top of the dash get only a fresh/hot mix depending on the air volume/fan speed/air distribution combination selected on the controls to the left of the radio.
2. The foot well vents which are located in the underside of the dash likewise directly over the driver's /passenger's ankles gets the same fresh/hot options depending again on the settings on the central air distribution controls
3. The vents in the center of the dash (the central ones over the radio) get COOLED AIR ONLY.
4. The two dash side vents located to the right of the glove box and to the left of the key slot have air supplies from all three sources; the fresh air intakes, the heat supply and the cooled air lines. If the fresh air intake is closed and the heat off, you can get AC through those vents. Otherwise you get a combination of fresh/hot/cooled air in both your and your passenger's face.
5. The little black diverter device located directly over the floor console and below/behind the ashtray delivers cooled air only to the foot wells.


Interestingly, Bentley makes no mention of the cooled air only outlets below/behind the ashtray and even more interesting, the Porsche owner's manual does not mention the foot well fresh/heat outlets.


Hope this adds to the body of knowledge.

[cactusdtd]

Ian,

FYI ....I recall a thread on this site by a fellow pelican who rerouted the footwell AC outlet to a clever vent device mounted on the floor/shifter console so as to deliver more AC to the middle of the cockpit.

Again.....great work

[telone2]

imcarthur, Well, that explains a lot. Unforturnantly, my 79 SC, isn't like that. Where is the sensor on the 79? Does the main blower fan run only when the dial is on "9"? I installed a new fan and have checked the fuses and relays. any thoughts? My fresh air blower doesn't work at all, but does that matter if heat is all that I am interested in? Thanks for the help on your web site. Very nice.

[imcarthur]

telone2

Your sensor is a small tube near the rearview mirror as pictured on Pg 1 of this post (I think). Have you tried to direct wire your main fan to see if it is working at all? They often fail. Other culprits include the fuses 1 & 2 on the fuse block in the engine compartment & the main relay for the fan in the same locale.

Ian

[imcarthur]

Dan

How's this? Can we call it the definitive air source diagram for 86 - 89 Autoheat yet?

Ian

Pic deleted - see below

[cactusdtd]

Ian,

I went back and consulted my references and, in the interest of research, took the p-car out for an hour run up into the hills and as a result i have one suggestion for the "definitive guide to auto heat 87-89". That is ....the side vents do not deliver fresh air at all. That is consistent with the owner's manual and my experience today. when the autoheat controller is switched to position 0, you can only get cooled air through those vents. when it is in position 1 - 9 you get hot air that you can blend with cooled / AC air. Technically therefore the diagram should indicate red/blue at the side vents. by the way.....sunny and 48 degrees .......perfect for a little "research".

great work........

[ausdilecce]

Actually, there really should be two pics, one pic for cars with factory air and one for cars without factory air..

cars WITH factory AC--
heat from: top vents, side vents, and footwell vents ( on the outsides of the footwells )
fresh air from: top vents, and footwell vents ( on the outsides of the footwells )
cooled air from: side vents, center vent, and center footwell vent

cars WITHOUT factory AC
heat from: top vents, side vents, and footwell vents
fresh air from: top vents, side vents, center vent, and footwell vents ( there is no center footwell vent ?)

Sorry imcarthur

[imcarthur]

Dan & ausdilecce

Here are the edited versions. Thanks for your input. Dan, I'm really sorry to have to make you take your car for a run 'in the interests of research'. That was above & beyond . . .

Edit: See revised pics in post below.

[cactusdtd]

Ladies and Gentlemen,

Please note the "Definitive Guide to Auto Heat 86-89 Porsche 911" is now available !!!!


Excellent job Ian.

May your spring arrive early so that the '87 can get back on those northern roads.

[imcarthur]

Design Meeting – Weissach Germany - Sometime in the '70s

Hans:
“Zee heating and silly AIR CONDITIONER must not interfere with zee driving experience. Vee must permit no more extra weight than is ABSOLUTELY necessary. It is also imperative that zis weight be distributed around zee automobile zo the balance is maintained.”

Dieter:
“This is a problem. Pass me the bag of dried mushrooms you brought in this morning, Hans. Where did you zay you picked them? Zey are very tasty.”

[Wil Ferch]

'Cept one thing.....

The pic describes my 85 auto heat perfectly....then why only "86 -89" in the pic title ??

Also...my top lever is a single lever...later models ( some?..all?) had two opposing levers for left/right control?

Wil

[ausdilecce]

Great work !

I cannot see any issues with either pic.. ( they match the owners manual I have in front of me )

[imcarthur]

Here you go Wil -




Now I suppose the manual heat guys will want one too . . .

[rob justice]

Question on cars fitted with Auto heat - As soon as I switch on the ignition - the blower fan in the engine bay starts running (pretty quick!) and no amount of twisting the dials makes any difference.
I pulled the engine bay fan relay to give the fan a break.
Is this normal or do I have a problem somewhere?
Cheers
Rob